Nonlinearity of a TDC circuit arises due to variations in a delay time of a delay element. In the related art, a technique is disclosed where, in order to reduce a spurious caused in an output of a PLL circuit due to a periodical deviation of a phase difference due to the nonlinearity of the TDC circuit, an amount of delay of the delay element that supplies a reference signal to the TDC circuit is controlled, an operation is performed by using a phase difference based on a phase difference error with respect to each delay amount prepared in advance in a lookup table and an actual delay amount, and calibration is performed during a phase calculation.
The delay amount of the delay element also varies depending on manufacturing conditions of a semiconductor device (not illustrated) in which the TDC circuit and the PLL circuit are incorporated or a temperature change during operation. Control of the delay amount gives an error component to the phase difference calculation. Therefore, it is desirable that the spurious can be reduced by controlling the delay amount, the given error component can be easily grasped, and the error component can be timely corrected at the time of phase calculation.